QML Planning (Bitcoin Core Dev Tech, May 2026)

A history and plan for the QML GUI — a rewrite of Bitcoin Core's desktop interface in Qt's QML language. After early progress on wallet controllers, nearly every contributor burned out, got a new job, or moved on, and the project stalled for months because fully replacing the Qt Widgets GUI seemed infeasible. It revived once LLMs (Codex, Claude) became very capable at QML; about 22 core feature gaps were identified and mostly filled over two to three months, with two new contributors joining.

A key advance is the test framework: a new TestBridge class that automates clicking through multiple screens and objects (there being no open-source equivalent to the commercial qt-squish), plus unit tests on models and controllers — described as the most impactful change since last year. The plan is to replace the Qt Widgets UI outright, reviewing the large QML codebase in one go rather than small chunks, and to publish preview, beta, and v1 milestones for users to test. Because the app was originally designed for mobile, a desktop redesign (for example the settings screen) is needed before v1, and development will be design-first going forward.